Many hybrid electrical vehicles (HEV's) include a high voltage battery that is used to supply power to one or more electric machines. One or more of the electric machines may be operated as motors to help propel the vehicle, and may also be operated as generators, which can be used to charge the battery. Batteries, such as those used in HEV's, may require a cooling system to help ensure that their temperature does not get too high. In addition, it may be desirable to ventilate the environment around the battery.
A number of alternatives exist for providing cooling and/or ventilation to the environment around a battery. For example, air can be drawn from the passenger compartment of the vehicle to cool and/or ventilate the battery. This method may be less than ideal, however, since the air in a passenger compartment is often warm, and may not be cool enough to adequately reduce the temperature of the battery. In addition, if the air from the environment around the battery is recirculated into the passenger compartment, it may have an adverse effect on the passenger compartment air temperature, and thus, passenger comfort.
One alternative is to use fresh ambient air from outside the vehicle to both cool and ventilate the battery. This method may also be less than ideal, since the ambient air may be too warm to adequately cool the battery, or it may be so cold that it is desirable to raise its temperature before it is allowed to contact the hot battery. Moreover, when using ambient air from outside the vehicle, measures must be taken to inhibit the influx of dust, water and other foreign matter.